Divide the dough into two equal pieces. Roll out one piece ⅛ in/0.3 cm thick and line the pie pan. Reserve the remaining dough, wrapped tightly, under refrigeration.
Combine the blueberries, sugar, and tapioca.
Roll out the remaining dough ⅛ in/0.3 cm thick. Lightly brush the edge of the lined pie dough with egg wash. Place the berry mixture into the